Alvero-Cruz José Ramón, Alvarez Carnero Elvis, Fernández-García José Carlos, Barrera Expósito Jesús, Carrillo de Albornoz Gil Margarita, Sardinha Luis B
Escuela de Medicina de la Educación Física y del Deporte, Facultad de Medicina, Universidad de Málaga, Málaga, España.
Med Clin (Barc). 2010 Jun 5;135(1):8-14. doi: 10.1016/j.medcli.2010.01.017. Epub 2010 Mar 26.
To determine the accuracy of body mass index (BMI), fat mass index (FMI) and fat-free mass index (FFMI) to find cut-off points related to overweight in adolescents aged 12-18 years.
150 adolescents were assessed (75 boys aged 14.81+/-1.86yr, height 168.8+/-8.8cm, weight 65.84+/-16kg and BMI 22.89+/-4.4kg x m(2), and 75 girls aged 14.88+/-1.94yr, height 159.4+/-7.6cm, weight 54.77+/-9.54kg and BMI 21.48+/-3.1kg x m(2)). Body composition was measured by using the deuterium dilution technique with an isotope ratio mass spectrometer and fat free mass hydration constants were applied. Taylor's age-related overweight classification was applied and receiver operating characteristic (ROC) curves analyses were performed. Areas under curve were calculated for every index (BMI, FMI and FFMI). Sensitivity and specificity values of BMI and FMI to diagnose overweight were evaluated.
Among boys, predictive positive values for BMI were 78.1% and 89.2% for FMI; predictive positive values in girls was 34.8% for BMI and 81.4% for FMI. Predictive negative values were 81.4% and 100% in boys and 98.1% and 100% in girls for BMI and FMI. Areas under curve of FMI for boys (0.988, 95%CI: 0.930-0.998) and girls (0.996, 95%CI: 0.943-1.000) showed high accuracy for overweight diagnose. Cutoff points of 4.58kg x m(2) in boys and 7.76kg x m(2) in girls for FMI and 23.07kg x m(2) in boys and 23.18kg x m(2) in girls for BMI had high sensitivity and specificity as indicators of overweight classification.
FMI showed high accuracy for overweight screening. Thus, our cut-off points may be useful as a tool to surveillance children's overweight on clinical and epidemiologic settings.
确定体重指数（BMI）、脂肪量指数（FMI）和去脂体重指数（FFMI）在找出12 - 18岁青少年超重相关切点方面的准确性。
对150名青少年进行评估（75名男孩，年龄14.81±1.86岁，身高168.8±8.8厘米，体重65.84±16千克，BMI为22.89±4.4千克/平方米；75名女孩，年龄14.88±1.94岁，身高159.4±7.6厘米，体重54.77±9.54千克，BMI为21.48±3.1千克/平方米）。采用同位素比质谱仪的氘稀释技术测量身体成分，并应用去脂体重水合常数。应用泰勒的年龄相关超重分类法，并进行受试者工作特征（ROC）曲线分析。计算每个指标（BMI、FMI和FFMI）的曲线下面积。评估BMI和FMI诊断超重的敏感性和特异性值。
在男孩中，BMI的预测阳性值为78.1%，FMI为89.2%；在女孩中，BMI的预测阳性值为34.8%，FMI为81.4%。BMI和FMI在男孩中的预测阴性值分别为81.4%和100%，在女孩中分别为98.1%和100%。男孩（0.988，95%CI：0.930 - 0.998）和女孩（0.996，95%CI：0.943 - 1.000）的FMI曲线下面积显示出对超重诊断的高准确性。FMI在男孩中的切点为4.58千克/平方米，女孩为7.76千克/平方米；BMI在男孩中的切点为23.07千克/平方米，女孩为23.18千克/平方米，作为超重分类指标具有高敏感性和特异性。
FMI在超重筛查中显示出高准确性。因此，我们的切点可能作为一种工具，在临床和流行病学环境中用于监测儿童超重情况。
